SiPM Photodetector Peripheral p+ Layer for Infrared Absorption
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Solution Overview
Problem
Silicon photomultipliers (SiPMs) used in in-vehicle LIDAR systems have a low infrared absorption rate, leading to suboptimal photon detection efficiency, which hinders accurate distance and shape identification of faraway targets.
Innovation Solution
The photodetector design incorporates a silicon layer with a p+ type layer having an impurity concentration higher than the silicon layer, a second semiconductor layer forming a pn boundary, and a peripheral p+ type layer with an impurity concentration at least 10 times higher than the epitaxial layer, enhancing the effective region for photon capture and detection.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If a conventional silicon photomultiplier structure is used, then the device can detect photons, but the infrared absorption rate is low resulting in suboptimal photon detection efficiency
Solution Approach 1:
The patent applies local quality by creating a peripheral p+ type layer with significantly higher impurity concentration (at least 10 times higher) than the epitaxial layer, specifically in the peripheral region of the photodetector. This localized modification of impurity concentration in the peripheral region enhances the effective region for photon capture without altering the overall device structure, thereby improving photon detection efficiency while maintaining the conventional SiPM architecture.
Solution Approach 2:
The patent changes the impurity concentration parameter by introducing a peripheral p+ type layer with impurity concentration at least 10 times higher than the epitaxial layer. This parameter change in the peripheral region expands the effective detection area and improves infrared absorption, directly addressing the low photon detection efficiency issue in conventional SiPMs.
2Measurement precision
If the impurity concentration of the peripheral p+ type layer is increased to expand the effective region, then photon detection efficiency improves, but the device structure becomes more complex
Solution Approach 1:
The patent introduces a peripheral p+ type layer with high impurity concentration specifically in the peripheral region, making the structure more complex only where needed to enhance photon capture. This localized structural modification improves photon detection efficiency without requiring a complete redesign of the entire device architecture.
Solution Approach 2:
The peripheral p+ type layer is nested within the existing photodetector structure, forming a concentric configuration where the high impurity concentration layer surrounds the lower impurity concentration epitaxial layer. This nested structure efficiently expands the detection region while maintaining a compact and integrated device design.
3Area of stationary object
If a peripheral p+ type layer with high impurity concentration is added, then the effective region for photon capture increases, but the manufacturing process becomes more difficult
Solution Approach 1:
The patent modifies the impurity concentration parameter by creating a peripheral p+ type layer with at least 10 times higher impurity concentration than the epitaxial layer. This parameter change can be achieved through standard semiconductor manufacturing techniques such as ion implantation or diffusion processes, allowing the expansion of the effective region without requiring fundamentally new manufacturing capabilities.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
This configuration significantly improves photon detection efficiency by increasing the effective region for photon capture, allowing for higher accuracy in detecting infrared light and enabling better identification of shapes and distances from targets.
Implementation Method 1
Silicon has a low infrared absorption rate, and thereby it is desirable to improve photon detection efficiency (PDE) in the SiPM
Implementation Method 2
a peripheral p+ type layer 26 is provided in an epitaxial layer 21... An impurity concentration of the peripheral p+ type layer 26 is at least 10 times higher than that of the epitaxial layer 21
Implementation Method 3
A first semiconductor layer 22 serves as a first implanted layer of a first conductivity type... A second semiconductor layer 23 of a second conductivity type is provided on the first semiconductor layer 22
Implementation Method 4
a photodetector that detects infrared light reflected from a target
Data Source
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AI summary
A photodetector includes: a silicon layer (21) provided on a first main surface of a semiconductor substrate (20) and of a first conductivity type; a first semiconductor layer (22) provided in the silicon layer (21), of a first conductivity type, and having an impurity concentration higher than a impurity concentration of the silicon layer (21); a second semiconductor layer (23) provided on the first semiconductor layer (22), of a second conductivity type, and forming a pn boundary with the first semiconductor layer (22); a third semiconductor layer (26) provided in the silicon layer (21), of a first conductivity type, having an impurity concentration higher than that of the silicon layer (21), and separated from the first semiconductor layer (22); a first electrode (31) connected to the silicon layer (21); and a second electrode (32) connected to the second semiconductor layer (23).